How to repostion/reset the selector closer to the object with mirror modifier still active?
I Just figured it out:




Place 3d cursor where you want it. 
Unselect Clipping on the Mirror Modifier. 
In tools, Set origin select Origin to 3D cursor. 
On the Mirror Modifier, re-select Clipping.  
Adjust the Merge limit to place the two sides back together.


That looks like it worked.